Flame retardant composition for use in styrenics

ABSTRACT

A method for flame-retarding styrenic resins is disclosed wherein the method comprises incorporating in compositions an effective amount of at least one flame retardant compound comprising both aliphatic and aromatic bromine.

I claim the benefit under Title 35, United States Code, §119 to U.S.Provisional Application Number 60/905,328; filed Mar. 7, 2007; entitledNew Flame Retardant Composition for use in Styrenics.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to flame retardants. More particularly,the present invention is related to flame retardants comprising bothaliphatic and aromatic bromine for use with styrenic resins.

2. Description of Related Art

Styrenic resins are well known in the synthetic organic polymer art as aclass of thermoplastics that offer excellent mechanical properties aswell as good chemical resistance. The properties that make styrenicsuseful for many applications as solid polymers also make them verydesirable as foamed polymers. A number of processes have been developedover the last forty years to prepare styrenic foams for a variety ofapplications, some of which require the use of flame retardants.

A flame retardant, such as a halogenated organic compound, is oftenincorporated into a formulated resin in order to render the resinresistant to ignition. It is known that brominated aliphatic compounds,brominated aromatic compounds, and mixtures thereof have been used insolid and foamed styrenic applications. Hexabromocyclododecane (HBCD) isone such known aliphatic brominated flame retardant that has been usedin foamed styrenic applications. HBCD is a highly brominated aliphaticflame retardant that has unusually high thermal stability, which resultsin excellent performance at low loading levels with a minimum effect onpolymer properties.

Recently there have been concerns about the health and environmentalimpact of some flame retardants including HBCD. Although scientificstudies have not necessarily shown significant risks to human health orthe environment, there are ongoing reviews by various regulatoryagencies that may result in reduced usage of HBCD. In the event thatthese agencies limit the usage of HBCD, extruded polystyrene foam andexpanded polystyrene foam manufacturers may be required to choose analternative flame retardant, and many may adopt a substitute before anyregulatory mandate. Thus, there exists a need for a flame retardantalternative to HBCD that is more environmentally friendly and maintainsall of the performance properties of HBCD.

WO 2007/057900 discloses polybrominated bisaryl compounds containingbromomethyl or bromomethylene groups, as well as flameproof polymericformulations comprising the compounds. These compounds are said toexhibit good thermal stability and to be particularly suitable forflame-retarding polystyrene thermoplastic foams. A process for makingthe polybrominated bisaryl compounds is also disclosed.

WO 2006/008738 discloses a process for the preparation of highly purepentabromobenzyl bromide, wherein the benzylic bromination reaction iscarried out in a suitable organic solvent in the presence of water andwherein the reaction temperature is such that it is sufficient toactivate the initiator but not high enough to consume a substantialamount thereof.

WO 2006/013554 discloses a styrenic polymer composition comprising aflame-retardant effective amount of a compound of formula (I):(C₆H(_(5-n))Y_(n))CH₂X, wherein X is Cl or Br; Y is Cl or Br; and n isan integer between 1 and 5; or a mixture of two or more of saidcompounds of formula (I) or their homologues and derivatives or otherBr-FRs.

GB 1,107,283 discloses a granular expandable polystyrene compositionthat contains as a fire-retardant a minor amount of a compound offormula Ar(Br)_(m)(Cl)_(n)R or Ar(Br)_(x)(Cl)_(y)OR where Ar is an arylresidue, m is 1-4, n is 0-2, x is 1 or more, y is 0 or an integer and Ris hydrogen, a straight or branched chain alkyl group which may behalogenated, a straight or branched chain alkenyl group or a halogenatedaryl group; there being at least 2 nuclear bromine atoms per molecule ofthe above compound. The compound may be tetrabromobenzene,tribromophenol, pentabromophenyl (allyl, ethyl or n-propyl) ether, anisomer of tribromotoluene or tribromophenyl allyl ether,chlorodibromotoluene, chlorodibromophenyl allyl ether, hexabromodiphenylether, dibromodiphenyl, dibromonaphthalene;2,4-dibromo-1-methylnaphthalene; 1,5-dibromoanthracene; pentabromophenyldibromopropyl ether, pentabromophenol or tetrabromochlorophenol. Thecomposition may also contain dicumyl or di-tert. butyl peroxide, tert.butyl peracetate or cumene hydroperoxide. The compositions may be madeby polymerizing styrene in the presence of the fire-retardant compound,polystyrene granules, benzoyl peroxide, water and petroleum ether asexpanding agent and the resulting polymer may be granulated, expanded byheating in steam and then moulded into a block.

GB 1,394,787 discloses a flame resistant polystyrene orstyrene-containing copolymer containing hexabromoxylene. There isfurther disclosed a self-extinguishing mouldable composition or mouldingcomprising polystyrene or a styrene-containing copolymers andhexabromoxylene in an amount of from 0.5 to 8.0 percent by weight, basedon the total weight of the mould able composition or moulding.

EP 0502333 discloses a process for preparing a mixture of brominated,non-condensed ring polyaromatics, which process comprises brominatingthe precursor non-condensed ring polyaromatic in the presence of abromination catalyst. The mixture has an average bromine number of 5.8to 6.2, more than about 55 GC area percent of the hexabromo homolog, anda reduced amount of light-end impurities.

U.S. Pat. No. 4,024,092 discloses polymer compositions having enhancedoxygen index values as measured by ASTM Method D-2863-70, whichcompositions contain effective amounts of a bromo or chloro derivativeof stilbene.

U.S. Pat. No. 5,039,729 discloses mixtures of brominated diphenylethanes, such mixtures containing a predominant amount ofhexabromodiphenyl ethane and having an average bromine number, basedupon GC area percent, of from about 6.7 to about 7.3. ABS basedformulations containing such mixtures and articles made from suchformulations are also disclosed.

U.S. Pat. No. 5,055,235 discloses a process for preparing a mixture ofbrominated, non-condensed ring polyaromatics, which process featuresmultiple bromination temperatures and multiple catalyst additions forbrominating the precursor non-condensed ring polyaromatic. The mixturehas an average bromine number of about 6 to about 8 bromine atoms permolecule, a low melting point range, and a low amount of light endimpurities.

U.S. Pat. Nos. 5,741,949 and 6,117,371 disclose a process for producinga brominated, non-fused aromatic composition that involves a continuousbromination in a continuous, mixed reactor such as a continuous stirredtank reactor. Bromine and the aromatic substrate, and optionally abromination catalyst, are continuously fed to a reaction zone to form areaction mixture, and the reaction mixture is continuously withdrawnfrom the reaction zone after an established average residence time.Bromination levels can be readily controlled by controlling the averageresidence time of the reaction mixture within the reaction zone.Preferred continuous processes also provide mixed, brominatedcompositions having product distributions which are substantiallybroader than that obtained by batch brominations conducted to achievethe same level of bromination. Preferred products thus have broadmelting ranges which are advantageous in compounding operations.

U.S. Pat. No. 5,821,393 discloses a process for the preparation of anaromatic bromoalkyl-substituted hydrocarbon compound, in which analkyl-substituted aromatic hydrocarbon compound is reacted with abrominating agent in the presence of water.

U.S. Pat. No. 6,743,825 discloses an additive mixture said to be usefulas a flame retardant. The mixture is comprised of (i) apoly(bromophenyl)alkane having in the molecule in the range of 13 to 60carbon atoms and in the range of two to four aryl groups and (ii) apoly(bromophenyl)bromoalkane having in the molecule in the range of 13to 60 carbon atoms and in the range of two to four aryl groups, saidpoly(bromophenyl)bromoalkane being in an amount which is greater than25wt %, based on the total weight of the additive mixture. A process formaking the poly(bromophenyl)bromoalkane is also disclosed.

The disclosures of the foregoing are incorporated herein by reference intheir entirety.

SUMMARY OF THE INVENTION

In evaluating alternatives for HBCD, it is important to maintain thegood properties of high efficiency at low usage levels and high thermalstability. According to the present invention, it has been found that asingle flame retardant compound containing both aliphatic and aromaticbromine can be used to flame retard styrenic resins, in particular,foamed styrenic resins. More surprisingly, the molecules containingaromatic bromine and benzylic bromine have been found to have thenecessary thermal stability and to be most efficient when compared bylab scale flammability tests.

More particularly, the present invention is directed to a method forflame retarding styrenic resins comprising incorporating an effectiveamount of at least one flame retardant compound comprising bothaliphatic and aromatic bromine.

In another aspect, the present invention is directed to an article ofmanufacture comprising a styrenic resin composition or foamed styrenicresin composition wherein said composition comprises an effective amountof at least one flame retardant compound comprising both aliphatic andaromatic bromine. In a preferred embodiment, in the article the flameretardant compound has an LOI of greater than 24 @ 5 phr when formulatedinto the resin in the range of 2-10 phr and a 5% weight loss based onTGA analysis of above 200° C.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

As noted above, the present invention relates to the use of compoundscomprising both aliphatic and aromatic bromine to flame retard styrenicresins.

Examples of target molecules within the scope of the present inventionare shown below:

wherein R¹, R², R³, R⁵, and R⁶ are independently selected from the groupconsisting of hydrogen and bromine, and R⁴ is selected from the groupconsisting of hydrogen, bromine, and CH₂Br;

wherein R⁷ through R¹⁴ are independently selected from the groupconsisting of hydrogen and bromine, R¹⁵ is selected from the groupconsisting of CH₂ and CHBr, and R¹⁶ is selected from the groupconsisting of CH₂, CHBr, and a fused ring;

wherein R¹⁷ through R²⁶ are independently selected from the groupconsisting of hydrogen and bromine, provided that no more than seven ofR¹⁷ through R²⁶ are bromine;

wherein R²⁷ is selected from the group consisting of alkyl, aryl,alkaryl, and SO₂, R²⁸ and R²⁹ are independently selected from the groupconsisting of hydrogen and alkyl, R³⁰, R³¹, R³⁶, and R³⁷ areindependently selected from the group consisting of methyl and CH₂Br,and R³² through R³⁵ are independently selected from the group consistingof hydrogen and bromine;

wherein R³⁸ through R⁴² are independently selected from the groupconsisting of hydrogen, bromine, CH₂Br, and alkyl, and R⁴³ through R⁴⁷are independently selected from the group consisting of hydrogen andbromine; and

wherein R⁴⁸ is selected from the group consisting of alkyl, aryl,alkaryl, and SO₂, R⁴⁹ through R⁵² are independently selected from thegroup consisting of CH₃ and CH2Br, R⁵³ through R⁵⁶ are independentlyselected from the group consisting of hydrogen and bromine, and R⁵⁷ andR⁵⁸ are independently selected from the group consisting of hydrogen andalkyl; provided that in each of the foregoing structures, there is atleast one aliphatic bromine and at least one aromatic bromine.

In the foregoing structural formulae, where an R group is:

-   a “fused ring”, it is a fused ring of from 5 to 8 carbon atoms;-   “alkyl”, it is an alkyl group of from 1 to 6 carbon atoms;-   “alkaryl”, it is an alkaryl group comprising at least one alkyl    group side chain of from 1 to 6 carbon atoms.

Examples of specific molecules that can be employed in the practice ofthe present invention include, but are not limited to,1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene, 1-bromoethyldibromobenzene, 1-bromoethyl tribromobenzene, 1-bromoethyltetrabromobenzene, bis-(1-bromoethyl)benzene,bis-(1-bromoethyl)bromobenzene, bis-(1-bromoethyl)dibromobenzene,bis-(1-bromoethyl)tribromobenzene, bis-(1-bromoethyl)tetrabromobenzene,9,10-dibromo-9,10-dihydro octabromoanthracene, 9,10-dibromo-9,10-dihydroseptabromoanthracene, 9,10-dibromo9,10-dihydro hexabromoanthracene,9,10-dibromo-9,10-dihydro pentabromoanthracene, 4-bromomethyltetrabromobenzyl 2,4,6-tribromophenyl ether, 4-bromomethyl benzyl2,4,6-tribromophenyl ether, and the like.

The most preferred molecules, owing to their balance of efficiency andthermal stability, are1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene and9,10-dibromo-9,10-dihydrooctabromo anthracene. The1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene is prepared in sucha away that there are eight major components and several minorcomponents that average to an aromatic bromine content of 5.5-6 bromineatoms and an average amount of 1.7-1.9 aliphatic bromine atoms.

The styrene resins employed in the practice of the present invention arestyrenic polymers, such as polystyrene, poly-(p-methylstyrene),poly-(α-methylstyrene), copolymers of styrene or α-methylstyrene withdienes or acrylic derivatives, such as, for example, styrene/butadiene,styrene/acrylonitrile, styrene/alkyl methacrylate, styrene/maleicanhydride,styrene/butadiene/ethylacrylate/styrene/acrylonitrile/methylacrylate,mixtures of high impact strength from styrene copolymers and anotherpolymer, such as, for example, from a polyacrylate, a diene polymer oran ethylene/propylene/diene terpolymer; and block copolymers of styrene,such as, for example, styrene/-butadiene/styrene,styrene/isoprene/styrene, styrene/ethylene/butylene/styrene orstyrene/ethylene/propoylene styrene. Styrenic polymers may additionallyor alternatively include graft copolymers of styrene or α-methylstyrenesuch as, for example, styrene on polybutadiene, styrene onpolybutadiene-styrene or polybutadieneacrylonitrile; styrene andacrylonitrile (or methacrylonitrile) on polybutadiene and copolymersthereof; styrene and maleic anhydride or maleimide on polybutadiene;sytrene, acrylonitrile, and maleic anhydride or maleimide onpolybutadiene; styrene, acrylonitrile, and methyl methacrylate onpolybutadiene, styrene and alkyl acrylates or methacrylates onpolybutadiene, styrene and acrylonitrile on ethylene/-propylene/dieneterpolymers, styrene and acrylonitrile on polyacrylates orpolymethacrylates, styrene and acrylonitrile on acrylate/butadienecopolymers, and the like.

Additionally, the styrenic resins can be in the form of foamed resins.These foamed resins can be comprised of any of the aforementionedstyrenic resins. Processes for making foamed resins are of two mainclasses: expanded polystyrene foams (EPS) and extruded polystyrene foams(XPS). The specific procedures for forming the foamed resins are welldefined in the art.

The flame retardants of the invention can be conventionally incorporatedinto the styrenic materials in flame retardant amounts. The amount ofthese flame retardants necessary for flame retardancy will depend uponthe particular brominated substrate employed and styrenic materialinvolved, as well as other flame retardants that might be included.Those of ordinary skill in the art will be readily able to incorporatean amount of the flame retardant which is necessary to achieve thedesired level of flame retardancy. As is well known, it is oftenpreferred to incorporate a brominated flame retardant with another flameretardant material, such as an inorganic compound, e.g. ferric oxide,zinc oxide, zinc borate, a group V element oxide such as a bismuth,arsenic, phosphorus or an antimony oxide.

In addition, foamed resins generally require additional materials toachieve the desired properties of the foam. These can include catalystsfor polymerization, blowing agents, emulsifiers, and stabilizers. Theexact compositions and quantities of other additives are known to thoseskilled in the art.

When selecting target molecules for screening, molecules containing onlyaliphatic, only aromatic, and a mix of aliphatic and aromatic brominewere considered. Examples of molecules used in the screening evaluationsare shown below:

Aliphatic only:

Aromatic only:

Aliphatic/Aromatic

Polymeric Aliphatic/Aromatic

In the above, the values of m and n were not rigorously specified in theanalytical data, but approximate numbers would be m=1 and n=1 in thefirst molecule and m=10 and n=1 in the second. This means that there isa higher amount of aliphatic (benzylic) bromine in the first moleculeand a relatively low level of aliphatic (benzylic) bromine in the secondmolecule. The LOI data support the premise that one needs both aliphaticand aromatic bromine, and that benzylic bromine is even better.

In the above structures, the notation Br₂ is intended to mean twobromine atoms, each attached at separate points to the phenyl ring.Similarly, Br₃, Br_(x), and Br_(y) refer to 3 bromines, x bromines, andy bromines, respectively, where x and y are independently integers offrom 1 to3.

The target molecule must have an Limiting Oxygen Index (LOI) of morethan 26 @ 5 phr and a 5% wt loss based on TGA analysis of more than 215°C. in order to be considered comparable to HBCD in end use EPS and XPSapplications. When evaluating molecules that contain only aliphaticbromine, the molecules were determined to be efficient as demonstratedby the LOI performance shown above; however, the molecules did not meetthe thermal criteria. Molecules containing only aromatic bromine werefound to be more thermally stable; however, did not appear to have thenecessary efficiency as determined by LOI.

Molecules containing both aliphatic and aromatic bromine were found tohave the best balance of efficiency and thermal stability. It wassurprisingly found that molecules containing aromatic bromine andbenzylic bromine have the best balance of efficiency and thermalstability. This is demonstrated by the series of dibromostyrenemolecules shown above where the LOI performance drops from 28-31 to 23when the benzylic bromine is removed. This observation is also confirmedin the diphenylethane series shown above wherein, when the benzylicbromine is removed, the LOI drops from 29 to 25. This series ofmolecules also demonstrates the necessity for having aromatic bromine onthe molecule in order to increase the thermal stability of the molecule.

EXAMPLES

Typical laboratory hand cast foams were prepared using the formulationslisted below. Lab preparation yielded foams with comparable densities.The foams were then evaluated by ASTM D2863-00 and UL-94. ASTM D2863-00is a test method used to determine the LOI, which is an indication offlame retardant effectiveness. Thermal stability is another criticalproperty and is measured using thernogravimetric analysis (TGA) in adynamic mode. Values from this test are reported as the temperature atwhich the test specimen lost five percent of its initial weight.

Formulations Hand Cast Nova 1994 PS resin  40 g Methylene chloride 178 gFlame Retardant 0.2 g-10 g Pentane  4 g

Experimental 1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene Step1: General Procedure for Aromatic Bromination of Diphenylethane (DPE):

A 500 mL round-bottom, 4-neck flask equipped masterflex pump, mechanicalstirrer, thermocouple, siltherm condenser, and HBr scrubber was chargedwith DPE (50 g, 0.274 mol), 100 mL of halocarbon solvent (dibromomethane(DBM), dichloroethane (EDC), or bromochloromethane (BCM)). The mixturewas stirred to dissolve the DPE and FeBr₃ or Fe (0.0075 mole) was added.Bromine (5.5 equivalents) was added dropwise over two hours. Thetemperature of the reaction increased via exotherm from 22° C. to 35° C.HBr evolution was measured to gage the reaction. After the reaction,additional solvent was added to the reaction (enough to make up a 1gram/3 mL product/solvent ratio) and 100 mL of deionized (DI) water or5% HBr was added. The reaction was stirred until it turned light orange.The layers were then phase separated. Approximately 10% (by weight) ofthe product was removed and dried under vacuum using a rotary evaporator(rotovap). The dried sample was analyzed for total organic bromide andiron content.

Theoretical Formula Weight 616.3 g/mol Molecular FormulaC₁₄H_(8.5)Br_(5.5) Organic Bromide 71.3 Fe (by ICP) <20 ppm1,1 ′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene

Step 2: Photolytic Procedure for Aliphatic Bromination of BromoDPE:

A 1 L round-bottom, 4-neck flask equipped with a 250 mL addition funnel,mechanical stirrer, thermocouple, siltherm condenser, and HBr scrubberwas charged with multibrominated DPE (152.2g; 0.245 mol) and 456 mL ofhalocarbon solvent (DBM, EDC, or BCM). The reaction mixture was heatedto reflux. Either a GE 250 watt reflector lamp or Hanovia UV blacklightswere used to catalyze the aliphatic bromination. Bromine (2 molarequivalents) was added dropwise over two hours. If solids were presentat the beginning of the reaction, they dissolved after about 10% of thebromine was added. If using EDC or BCM, some solids may precipitateduring the last 10% of the bromine addition. Stirring of the reactionwas continued for 3-4 hours after the bromine addition and was monitoredby HBr evolution. The reaction mixture was either rotovapped or solventevaporated and filtered to isolate the product. Yield of the reactionwas 50-95% depending on the method of isolation.

1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene

Step 2: AIBN Procedure for Aliphatic Bromination of BromoDPE:

A 1 L round-bottom, 4-neck flask equipped with a mechanical stirrer,thermocouple, and a siltherm condenser was charged with multibrominatedDPE (50 g; 0.81 mole) and 40 mL of halocarbon solvent (DBM, EDC, orBCM), bromine (28.5 g; 0.18 mol), and 40 mL of DI water. The reactionmixture was heated to 70° C. A slurry of 1.1 g AIBN and 5 mL of waterwas added over three hours. The reaction was stirred at 70° C. for twoadditional hours after the last AIBN charge. The reaction mixture wasthen cooled and the aqueous layer was phase separated. The reactionmixture was washed with DI water and NaHSO₃ to remove any residualbromine, then DI water. The solvent was removed by rotovap or filteredto isolate the product. Yield of the reaction ranged from 62-95%.

The target analysis of the final product is:

Theoretical Formula Weight 774.1 g/mol Molecular FormulaC₁₄H_(6.5)Br_(7.5) Organic Bromide 76.7  Hydrolizable Bromide >15%Target Aromatic Bromine 5.5-6   Target Aliphatic Bromine 1.5-2.0 AverageAromatic Bromine 6.0 Average Aliphatic Bromine 1.6 Inorganic Bromide <1% TGA (5% weight loss) >210° C. Isothermal TGA (200° C./30 min) ~88%

In view of the many changes and modifications that can be made withoutdeparting from principles underlying the invention, reference should bemade to the appended claims for an understanding of the scope of theprotection to be afforded the invention.

1. A method for flame-retarding styrenic resins and foamed styrenic resins comprising incorporating an effective amount of at least one flame retardant compound comprising both aliphatic and aromatic bromine.
 2. The method of claim 1 wherein the flame retardant compound is selected from the group consisting of:

wherein R¹, R², R³, R⁵, and R⁶ are independently selected from the group consisting of hydrogen and bromine, and R⁴ is selected from the group consisting of hydrogen, bromine, and CH₂Br;

wherein R⁷ through R¹⁴ are independently selected from the group consisting of hydrogen and bromine, R¹⁵ is selected from the group consisting of CH₂ and CHBr, and R¹⁶ is selected from the group consisting of CH₂, CHBr, and a fused ring;

wherein R¹⁷ through R²⁶ are independently selected from the group consisting of hydrogen and bromine, provided that no more than seven of R¹⁷ through R²⁶ are bromine;

wherein R²⁷ is selected from the group consisting of alkyl, aryl, alkaryl, and SO₂, R²⁸ and R²⁹ are independently selected from the group consisting of hydrogen and alkyl, R³⁰, R³¹, R³⁶, and R³⁷ are independently selected from the group consisting of methyl and CH₂Br, and R³² through R³⁵ are independently selected from the group consisting of hydrogen and bromine;

wherein R³⁸ through R⁴² are independently selected from the group consisting of hydrogen, bromine, CH₂Br, and alkyl, and R⁴³ through R⁴⁷ are independently selected from the group consisting of hydrogen and bromine; and

wherein R⁴⁸ is selected from the group consisting of alkyl, aryl, alkaryl, and SO₂, R⁴⁹ through R⁵² are independently selected from the group consisting of CH₃ and CH₂Br, R⁵³ through R⁵⁶ are independently selected from the group consisting of hydrogen and bromine, and R⁵⁷ and R⁵⁸ are independently selected from the group consisting of hydrogen and alkyl; provided that in each of the foregoing structures, there is at least one aliphatic bromine and at least one aromatic bromine.
 3. The method of claim 1 wherein the flame retardant compound is selected from the group consisting of:


4. The method of claim 1 wherein the flame retardant compound is selected from the group consisting of 1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene, 1-bromoethyl dibromobenzene, 1-bromoethyl tribromobenzene, 1-bromoethyl tetrabromobenzene, bis-(1-bromoethyl)benzene, bis-(1-bromoethyl)bromobenzene, bis-(1-bromoethyl)dibromobenzene, bis-(1-bromoethyl)tribromobenzene, bis-(1-bromoethyl)tetrabromobenzene, 9,10-dibromo-9,10-dihydro octabromoanthracene, 9,10-dibromo-9,10-dihydro septabromoanthracene, 9,10-dibromo-9,10-dihydro hexabromoanthracene, 9,10-dibromo-9,10-dihydro pentabromoanthracene, 4-bromomethyl tetrabromobenzyl 2,4,6-tribromophenyl ether, and 4-bromomethyl benzyl 2,4,6-tribromophenyl ether.
 5. The method of claim 4 wherein the flame retardant compound is selected from the group consisting of 1,1 ′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene and 9,10-dibromo-9,10-dihydrooctabromo anthracene.
 6. The method of claim 5 wherein the flame retardant compound is 1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene.
 7. The method of claim 1 wherein the flame retardant compound has an LOI of greater than 26 @ 5 phr and a 5% weight loss based on TGA analysis of above 215° C.
 8. An article of manufacture comprising a styrenic resin composition or foamed styrenic resin composition wherein said composition comprises an effective amount of at least one flame retardant compound comprising both aliphatic and aromatic bromine.
 9. The article of claim 8 wherein the flame retardant compound is selected from the group consisting of:

wherein R¹, R², R³, R⁵, and R⁶ are independently selected from the group consisting of hydrogen and bromine, and R⁴ is selected from the group consisting of hydrogen, bromine, and CH₂Br;

wherein R⁷ through R¹⁴ are independently selected from the group consisting of hydrogen and bromine, R¹⁵ is selected from the group consisting of CH₂ and CHBr, and R¹⁶ is selected from the group consisting of CH₂, CHBr, and a fused ring;

wherein R¹⁷ through R²⁶ are independently selected from the group consisting of hydrogen and bromine, provided that no more than seven of R¹⁷ through R²⁶ are bromine;

wherein R²⁷ is selected from the group consisting of alkyl, aryl, alkaryl, and SO₂, R²⁸ and R²⁹ are independently selected from the group consisting of hydrogen and alkyl, R³⁰, R³¹, R³⁶, and R³⁷ are independently selected from the group consisting of methyl and CH₂Br, and R³² through R³⁵ are independently selected from the group consisting of hydrogen and bromine;

wherein R³⁸ through R⁴² are independently selected from the group consisting of hydrogen, bromine, CH₂Br, and alkyl, and R⁴³ through R⁴⁷ are independently selected from the group consisting of hydrogen and bromine; and

wherein R⁴⁸ is selected from the group consisting of alkyl, aryl, alkaryl, and SO₂, R⁴⁹ through R⁵² are independently selected from the group consisting of CH₃ and CH₂Br, R⁵³ through R⁵⁶ are independently selected from the group consisting of hydrogen and bromine, and R⁵⁷ and R⁵⁸ are independently selected from the group consisting of hydrogen and alkyl; provided that in each of the foregoing structures, there is at least one aliphatic bromine and at least one aromatic bromine.
 10. The article of claim 8 wherein the flame retardant compound is selected from the group consisting of:


11. The article of claim 8 wherein the flame retardant compound is selected from the group consisting of 1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene, 1-bromoethyl dibromobenzene, 1-bromoethyl tribromobenzene, 1-bromoethyl tetrabromobenzene, bis-(1-bromoethyl)benzene, bis-(1-bromoethyl)bromobenzene, bis-(1-bromoethyl)dibromobenzene, bis-(1-bromoethyl)tribromobenzene, bis-(1-bromoethyl)tetrabromobenzene, 9,10-dibromo-9,10-dihydro octabromoanthracene, 9,10-dibromo-9,10-dihydro septabromoanthracene, 9,10-dibromo-9,10-dihydro hexabromoanthracene, 9,10-dibromo-9,10-dihydro pentabromoanthracene, 4-bromomethyl tetrabromobenzyl 2,4,6-tribromophenyl ether, and 4-bromomethyl benzyl 2,4,6-tribromophenyl ether.
 12. The article of claim 11 wherein the flame retardant compound is selected from the group consisting of 1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene and 9,10-dibromo-9,10-dihydrooctabromo anthracene.
 13. The article of claim 12 wherein the flame retardant compound is 1,1′-(1,2-dibromo-1,2-ethanediyl)bis-tribromobenzene.
 14. The article of claim 8 wherein the flame retardant compound has an LOI of greater than 24 @ 5 phr when formulated into the resin in the range of 2-10 phr and a 5% weight loss based on TGA analysis of above 200° C. 